The ISO 20457 tolerance table, found within the standard’s PDF, is a cornerstone of modern geometric product specification. It translates the abstract concept of “general tolerance” into specific, actionable numbers for linear dimensions, angles, flatness, straightness, perpendicularity, and runout. By organizing these values into four clear classes (f, m, c, v), the standard balances manufacturing economy with functional assurance. For any design engineer or manufacturing professional, understanding how to read and apply the tables in ISO 20457 is not a niche skill—it is a fundamental practice that turns a drawing into a reliable, producible product.
Practical application guidance
Always confirm that the table shows and includes the separate columns for parting line (typically labelled “F” for “flash line” in German-influenced documents). iso 20457 tolerance table pdf